Magnetostatically coupled thin-film magnetic memory devices

ABSTRACT

A multilayer magnetostatically coupled thin-film magnetic memory device comprising, in succession, a first magnetic film, a chromium-copper alloy conducting layer having a reasonably low resistivity, a smoothing layer, and a second magnetic film. Due to the presence of chromium in the chromium-copper alloy forming the conducting layer, when the second magnetic film is subsequently formed on the smoothing layer at an elevated temperature, the resulting grain growth and surface roughness of the chromium-copper alloy conducting layer are less severe than with other known metals having reasonably low resistivity values (e.g., copper, silver, gold, and aluminum) previously suggested for use as conducting layers in magnetostatically coupled thinfilm magnetic memory devices. Consequently, the effects of grain growth and surface roughness of the chromium-copper alloy conducting layer on the static magnetic properties of the second magnetic film are less severe than heretofore, and a smaller combined thickness of the conducting layer and smoothing layer is required to make the values of the static magnetic properties of the first and second magnetic films nearly equal. As a further result of the smaller combined thickness of the conducting and smoothing layers made possible by the use of chromium in the chromium-copper alloy, an improved magnetostatic coupling between the two magnetic films is obtained. An alternative multiplayer magnetostatically coupled thin-film magnetic memory device having no smoothing layer is also disclosed for use in less stringent applications where very close matching of the values of the static magnetic properties of the two magnetic films is not required.

United States Patent Franklin et al.

[54] MAGNETOSTATICALLY COUPLED THIN-FILM MAGNETIC MEMORY DEVICES [72]Inventors: Dennis M. Franklin, Randolph; Richard M. Hornreich, Sudbury;Harvey Rubinstein, Lynnfield, all of Mass.

[73] Assignee: Sylvania Electric Products, Inc.

[22] Filed: Dec. 19, 1969 [21] Appl. No.: 886,515

[52] US. Cl..340/174 QA, 340/174 NA, 340/174 PC Primary Examiner-StanleyM. Urynowicz, Jr. AttorneyArthur C. Johnson et al.

[451 Oct. 31, 1972 ABSTRACT A multilayer magnetostatically coupledthin-film magnetic memory device comprising, in succession, a firstmagnetic film, a chromium-copper alloy conducting layer having areasonably low resistivity, a smoothing layer, and a second magneticfilm. Due to the presence of chromium in the chromium-copper alloyforming the conducting layer, when the second magnetic film issubsequently formed on the smoothing layer at an elevated temperature,the resulting grain growth and surface roughness of the chromiumcopperalloy conducting layer are less severe than with other known metalshaving reasonably low resistivity values (e.g., copper, silver, gold,and aluminum) previously suggested for use as conducting layers inmagnetostatically coupled thin-film magnetic memory devices.Consequently, the effects of grain growth and surface roughness of thechromium-copper alloy conducting layer on the static magnetic propertiesof the second magnetic film are less severe than heretofore, and asmaller combined thickness of the conducting layer and smoothing layeris required to make the values of the static magnetic properties of thefirst and second magnetic films nearly equal. As a further result of thesmaller combined thickness of the conducting and smoothing layers madepossible by the use of chromium in the chromium-copper alloy, animproved magnetostatic coupling between the two magnetic films isobtained.

ge t app ications where very close matchin of the va ues o the staticmagnetic properties of he two magnetic films is not required.

20 Claims, 2 Drawing Figures MAGNETIC FILM (MAGNETOSTRICTIVE ORMAGNETOSTRICTIVE) NON SMOOTHING LAYER (e.g.,SiO,SiO ,Ti,Mo,W,Cr orTo)HROMIUM -COPPER ALLOY CONDUCTING LAYER GNETIC FILM (MAGNETOSTRICTIVE ORNON- MAGNETOSTRICTIVE SUBSTRATE (e.g., GLASS OR QUARTZ) PATENTEBucm m2 I3.701.983

MAGNETlC FILM (MAGNETOSTRICTIVE OR NON- MAGNETOSTRICTIVE) SMOOTHINGLAYER (elg.,SiO,SiO ,Ti,M0,W,Cr or Tc) HROMlUM-COPPER ALLOY CONDUCTINGLAYER GNETIC FILM (MAGNETOSTRICTIVE OR NON- MAGNETOSTR ICTIVE SUBSTRATE(e.g., GLASS OR QUARTZ) FIG. I

I6 MAGNETIC FILM (MAGNETOSTRICTIVE 0R NON- MAGNETOSTRICTIVE) CHROMIUM-COPPER ALLOY CONDUCTING LAYER l3 MAGNETIC FILM (MAGNETOSTRICTIVE 0R NON-MAGNETOSTRICTIVE) l2 SUBSTRATE (e.g.,GLASS OR QUARTZ) FIG.2

INVENTORS DENNIS M. FRANKLIN RICHARD M. HORNREICH HARVEY RUBINSTEINMAGNETOSTATICALLY COUPLED THIN-FILM MAGNETIC MEMORY DEVICES BACKGROUNDOF THE INVENTION The present invention relates to thin-film magneticdevices and, more particularly, to magnetostatically coupled thin-filmmagnetic memory devices.

Magnetostatically coupled thin-film magnetic memory devices, alsocommonly referred to as coupled-film or closed-flux devices, are wellknown to those skilled in the art. The advantages offered bymagnetostatically coupled thin-film magnetic memory devices, namely,smaller memory cell or device size, greater signal amplitudes, andhigher packing density, are also well known to those skilled in the art.A typical magnetostatically coupled thin-film magnetic memory device, assuggested by the prior art, includes a pair of magnetic films, forexample, vacuum-deposited Permalloy or Cobalt-permalloy (ternary alloy)films, separated by vacuum-deposited conducting layer, for example, awrite-sense conducting layer, having a reasonably low resistivity (highconductivity). Some materials having reasonably low resistivity valueswhich have been suggested for use as conducting layers inmagnetostatically coupled thin-film devices of the above type includecopper, silver, gold, and aluminum.

As an improved variation of the three-layer device briefly describedabove, it has been suggested in the prior art to separate the twomagnetic films by a conducting laycr having a reasonably lowresistivity, and a smoothing layer directly overlying the conductinglayer of a material such as silicon monoxide, titanium, or molybdenum.The smoothing layer serves in known fashion to alleviate large-graingrowth and surface roughness problems associated with the use of aconducting layer of pure copper, silver, gold, or aluminum by smoothingout the peaks and filling in the valleys of the top surface of theconducting layer thereby providing a reasonably smooth surface uponwhich the upper magnetic film can be deposited. As is well known, as aresult of using a smoothing layer in conjunction with the conductinglayer, the static magnetic properties of the upper magnetic film, suchas wall-motion coercive force (l-l angular dispersion (0: and anisotropyfield (l-l are made to have reasonable, acceptable values for manystorage applications, these values being more nearly equal to the valuesof the static magnetic properties of the bottom magnetic film.

Ideally, for most effective utilization, a magnetostatically coupledthin-film magnetic memory device should satisfy certain basicrequirements. Among these basic requirements is that the upper and lowermagnetic films have nearly equal values of static magnetic properties sothat the films respond similarly when exposed to applied magnetic fieldsand, at the same time, not adversely affect adjacent devices.Additionally, the two magnetic films should be spaced apart by as smalla distance as possible to provide the most effective magnetostaticcoupling between the two films. That is, the conducting layer or, whereemployed, the combination of the conducting layer and the smoothinglayer, should have as small a thickness as possible. In addition, theconducting layer should have a reasonably low resistivity (that is, ahigh conductivity) to enable use of low drive power levels (during writemode of operation) and to provide minimum attenuation of sense signals(during read mode of operation Further, the conducting layer should notbe characterized by serious grain size and surface roughness problemsnecessitating a very thick smoothing layer to avoid degradation of thestatic magnetic properties of the upper magnetic film, particularly atrelatively high deposition temperatures, e.g., 275-350C, as in the caseof the deposition of certain magnetostrictive magnetic films. As apractical matter, and also from a cost standpoint, the materials fromwhich the ideal magnetostatically coupled thin-film magnetic memorydevice is fabricated should be amenable to simple deposition and etchingoperations so as to be readily fabricated by batch-processingtechniques, and the cost of the various materials employed should bereasonably low.

Although the devices suggested by the prior art, as v discussedhereinabove, satisfy, several of the abovestated requirements for anideal magnetostatically coupled thin-film magnetic memory device, theydo not satisfy all or most of the stated requirements. For example, whenpure copper, silver, gold or aluminum is used as a conducting layer toseparate the upper and lower magnetic films of a magnetostaticallycoupled thin-film device (no smoothing layer), rather severe graingrowth takes place in the conducting layer during the formation of theupper magnetic film, particularly at higher temperatures (for example,275-350C), causing the values of the static magnetic properties of theupper magnetic film to differ from normal desirable values and todiffer, often significantly, from the values of the static magneticproperties of the lower magnetic film. When a smoothing layer, whetheran insulating layer (such as silicon monoxide) or a refractory metallayer (such as molybdenum, titanium, or tungsten), has been used inconjunction with the pure metal conducting'layer, the thickness of thesmoothing layer required to achieve the desired or optimum values ofstatic magnetic properties in the upper magnetic film has generally beenquite great, and often much greater than the thickness of the conductinglayer, thereby increasing the effective spacing between the two magneticfilms and causing a loss of magnetostatic coupling between the twomagnetic films. By way of example, when pure copper of a thickness of2,000A is used as a conducting layer for separating magnetostrictivemagnetic films having deposition temperatures of 2753 50 C, and siliconmonoxide is used as a smoothing layer, the silicon monoxide smoothinglayer must have a thickness at least three times the thickness of thecopper conducting layer to achieve satisfactory values of the staticmagnetic properties of the upper magnetic film.

As a partial solution to large-grain growth and surface roughnessproblems, it has been suggested to deposit the conducting layer (copper,for example) at very low temperatures, for example, lC, and to thendeposit the smoothing layer (if any) and the upper magnetic film at theusual higher temperatures. This procedure is commonly referred to astemperature cycling. However, temperature cycling introducesother'problems in requiring the use of costly liquid nitrogen coolingequipment within the vacuum chamber of the film-deposition apparatus, anarrangement which is not readily accomplished.

In addition to the abovementioned problems, gold is relatively expensiveand relatively difficult to etch, and molybdenum, titanium, and tungstenare relatively difficult to deposit. Aluminum, in addition to being theleast desirable of the abovementioned pure metals for use as aconducting layer, because of its higher resistivity, does not lenditself to simple soldering operations as when it is desired to connectelectrical leads thereto.

BRIEF SUMMARY OF THE INVENTION Briefly, in accordance with the presentinvention, a multilayer magnetic thin-film device is provided inaccordance with a first embodiment which satisfies most of theabovestated requirements for an ideal magnetic thin-film device andwhich overcomes most of the problems and difficulties associated withthe prior art devices. Briefly, the multilayer magnetic thin-film deviceof the first embodiment includes a first, lower magnetic film, a second,upper magnetic film, and a chromium-copper alloy conducting layer and asmoothing layer between the first and second magnetic films. Because ofthe presence of chromium in the chromium-copper alloy conducting layer,the resulting grain growth and surface roughness produced in thechromium-copper alloy conducting layer during the subsequent formationof the upper magnetic film, as discussed previously, are less severethat with pure copper or other well known pure metals previouslysuggested for use as conducting layers in multilayer magnetic thin-filmdevices. Consequently, the efi'ects of grain growth and surfaceroughness of the chromiumcopper alloy conducting layer on the staticmagnetic properties of the upper magnetic film are less severe thanheretofore, and a smaller combined thickness of the conducting layer andsmoothing layer is required to make the values of the static magneticproperties of the upper and lower magnetic films more nearly equal. As afurther result of the smaller combined thickness of the conducting andsmoothing layers made possible by the use of chromium in thechromium-copper alloy, an improved magnetostatic coupling between theupper and lower magnetic films is obtained. In addition, the chromium inthe chromium-copper alloy conducting layers, when present in smallamounts, for example, about one-quarter of one percent by weight of thechromium-copper mixture from which the conducting layer is formed,results in an overall resistivity for the chromium-copper alloyconducting layer which is reasonably low and, therefore, acceptable foruse in a multilayer magnetic thin-film device.

An alternative multilayer magnetic thin-film device having no smoothinglayer is also provided in accordance with the invention for use in lessstringent applications where very close matching of the values of thestatic magnetic properties of the upper and lower magnetic films is notrequired.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a side elevational view of amultilayer magnetostatically-coupled thin-film magnetic memory devicedisposed on a substrate in accordance with a first embodiment of theinvention; and

FIG. 2 is a side elevational view of a multilayer magnetostaticallycoupled thin-film magnetic memory device disposed on a substrate inaccordance with an alternative embodiment of the invention.

4 DETAILED DESCRIPTION or THE INVENTION Memory Device Magnetic FirstEmbodiment-FIG. 1

Referring to FIG. 1, there is shown in a side elevational view amultilayer magnetostatically coupled thinfilm magnetic memory device 1disposed on a substrate 2 in accordance with a first embodiment of theinvention. As shown in FIG. 1, the multilayer magnetostatically coupledthin-film device 1 comprises, in succession, a first magnetic film 3, achromium-copper alloy conducting layer 4, for example, a write-senseconducting layer, a smoothing layer 5, and a second magnetic film 6.Although not indicated in FIG. 1, an additional conducting layer may beprovided above the second (upper) magnetic film and insulated therefromfor use as a halflselect line in certain types of coincident-currentmemories, the other half-select line being the conducting layer 4. Byway of examples of some materials which may be employed to fabricate themagnetostatically coupled thin-film memory device 1 of FIG. 1, inaddition to the chromium-copper alloy conducting layer 4, the magneticfilms 3 and 6 may be of a vacuumdeposited magnetostrictive ornon-magnetostrictive Permalloy, Cobalt-Permalloy, or manganese-Permalloymaterial, and the smoothing layer 5 may be of vacuumdeposited siliconmonoxide (SiO), silicon dioxide (SiO molybdenum (Mo), tungsten (W),chromium (Cr), or tantalum (Ta). It is preferred, however, that thesmoothing layer 5 be of silicon monoxide due to the relative ease withwhich such material is deposited. The substrate 2, on which the memorydevice 1 is formed, may be of glass or quartz.

A significant aspect of the present invention is the use of achromium-copper alloy for forming the conducting layer 4. The basicproblem in using pure copper (as well as other pure metals), as statedhereinabove, is the tendency of the pure copper to form large grainsduring the deposition of an upper magnetic film. More specifically,during the deposition of the upper magnetic film, the temperature of thepure copper conducting layer increases to the temperature of the uppermagnetic film during the deposition thereof, large-grain growth takesplace in the copper, and a surface roughness is produced in the copperwhich is directly proportional to the grain size of the copper. It isbelieved that the surface roughness of the pure copper conducting layeris caused by anisotropic growth rates in the copper in differentcrystallographic directions. The resulting effect of the large graingrowth and surface roughness in the copper is to degrade the staticmagnetic properties of the upper magnetic film by increasing the valuesof these properties above normal values. As also discussed hereinbefore,even when a smoothing layer is employed to alleviate large-grain growthand surface roughness problems associated with the use of pure copper asa conducting layer, the thickness of the smoothing layer required toachieve the desired values of static magnetic properties in the uppermagnetic film can be substantial, particularly in the case of certainmagnetostrictive upper and lower magnetic films deposited attemperatures of approximately 275350C, thereby leading to a loss inmagnetostatic coupling between the two films because of the increasedeffective spacing therebetween.

In accordance with the present invention, a small amount of chromium isused together with copper to provide a chromium-copper melt mixture fromwhich the chromium-copper alloy conducting layer is then formed. By wayof example, the chromium-copper melt mixture may include aboutone-quarter of one percent by weight of chromium. The effect of the useof chromium as part of the chromium-copper alloy conducting layer is toreduce the grain growth and surface roughness in the chromium-copperalloy conducting layer by inhibiting large grain growth in the copperduring the subsequent deposition of the upper magnetic film. As aconsequence of using the chromium in the chromium-copper alloyconducting layer, it is possible to use an accompanying smoothing layerof a thickness lessthan (one-half, for example) to nearly equal thethickness of the chromium-copper alloy conducting layer for smoothingthe chromium-copper alloy conducting layer and for achieving the normalvalues of static magnetic properties in the upper magnetic film. It isto be noted that while the presence of one-fourth percent chromium byweight of the chromium-copper melt mixture from which thechromium-copper alloy conducting layer is formed results in an increasein the resistivity of pure copper by approximately 50 percent, fromapproximately 1.7 X l0 ohm-cm to approximately 2.5 X 10*ohm-cm, thisincrease in resistivity is considered an acceptable increase, theresultant resistivity being less than pure aluminum and approximatelyequal to pure gold, for example, It is also contemplated in accordancewith the present invention that more or less chromium may be used. Forexample, as little as one-tenth of one percent of chromium (by weight)may be used in a chromium-copper melt mixture and still inhibit graingrowth effectively. For short write-sense conducting layers (e.g., lessthan 1 foot), as much as one-half of one percent chromium (by weight)may be used in a chromium-copper melt mixture.

A highlysatisfactory magnetostatically-coupled thinfilm magnetic memorydevice such as shown in FIG. 1 was constructed in the following manner.A magnetostrictive Permalloy material, 60% Ni/40% Fe, was vacuumdeposited onto a glass substrate, at a temperature of approximately280C, to a thickness of 1,000 A to produce the lower magnetic film. Thecomposition of the deposited lower magnetic film was 45% Ni/55% Fe. Achromium-copper alloy conducting layer was then vacuum-deposited ontothe lower magnetic film from a chromium-copper melt mixture containingonefourth percent chromium by weight to a thickness of 3,000A. Thetemperature of the assembly during the deposition of the chromium-copperconducting layer was 100C. A silicon monoxide smoothing layer was thenvacuum-deposited onto the chromium-copper alloy conducting layer to athickness of 2,500A. The temperature of the assembly during thedeposition of the silicon monoxide smoothing layer was 200C. A secondmagnetic film was then formed, on the silicon monoxide smoothing layer,to a thickness of 1,000A by vacuum-depositing magnetostrictive Permalloymaterial, also 60% Ni/40% Fe, at an assembly temperature ofapproximately 280C. The composition of the deposited second magneticfilm was 45% Ni/55% Fe.

With the above materials and values, the wall-motion coercive force I-Iof the second (upper) magnetic film was 5.5 Oersteds, theangulardispersion a was 2.5, and the anisotropy field H, was 8 Oersteds, thesevalues consitituting normal, desirable values. The corresponding valuesof H a and H, for the first (lower) magnetic film were 5 Oersteds, 2,and 8 Oersteds, respectively. As is evident from the above example, thestatic magnetic properties of the upper and lower magnetic films werenearly the same while at the same time the spacing between .the twomagnetic films was maintained at a relatively small value (5,500A)thereby insuring effective magnetostatic coupling between the twomagnetic films.

Many variations are possible in the above described specific example.For example, the upper and lower magnetostrictive Permalloy magneticfilms may each have a thickness of 5002,000A and be vacuumdeposited at atemperature of 275-350C. The thickness of the chromium-copper alloyconducting layer may vary from a minimum of 3,000A to a max imum of 2microns (20,000A), and the thickness of the accompanying siliconmonoxide smoothing layer may vary from a minimum of 1,500A(corresponding to a 3,000A chromium-copper alloy conducting layer) to amaximum of 1.5 microns (corresponding to a 2 micron chromium-copperalloy conducting layer). The temperature of the assembly during thedeposition of the chromium-copper alloy conducting layer or the siliconmonoxide smoothing layer may be l00-200C. As to the use of pure copperas a conducting layer, experimentation has indicated that a pure copperconducting layer having a thickness of 2 microns, when used with certainmagnetostrictive Permalloy upper and lower magnetic films (e.g., 60%Ni/40% Fe) deposited at 275350C, cannot be smoothed by any reasonablelayer of silicon monoxide to produce a good quality upper magnetic film.

In addition to the abovedescribed specific example, it is possible tofabricate a multilayer device similar in all respects to the device ofthe above specific example with the exception of usingnon-magnetostrictive magnetic films instead of the magnetostrictivemagnetic films and using a temperature during deposition of 200325C. Asuitable non-magnetostrictive material is an Ni/20% Fe Permalloymaterial. It may also be possible in this case to use a smoothing layerof a thickness less than that given above due to the less sever graingrowth resulting from the use of lower temperatures during deposition.Magnetostatically-Coupled Thin-Film Magnetic Memory Device Thin-filmMagnetic Memory Device Alternative Embodiment-FIG. 2

Referring now to FIG. 2, there is shown in a side elevational view amultilayer magnetostatically coupled thin-film magnetic memory device 10deposed on a substrate 12 in accordance with an alternative embodimentof the invention. As shown in FIG. 2, the multilayer magnetostaticallycoupled thin-film device 10 comprises, in succession, a first magneticfilm 13, a chromium-copper alloy conducting layer 14, for example, awrite-sense conducting layer, and a second magnetic film 16. As in thecase of the multilayer memory device 1 of FIG. 1, the magnetic films 13and 16 may be of a vacuum-deposited magnetostrictive ornon-magnetostrictive Permalloy, Cobalt-Permalloy, or manganese-Permalloymaterial. The substrate 12 may be of glass or quartz. It is apparenttherefore, that the multilayer memory device of FIG. 2 is similar to themultilayer memory device 1 of FIG. 1 with the exception that nosmoothing layer is used in the multilayer memory device 10 of FIG. 2.The particular multilayer memory device 10 of FIG. 2 may be employed inapplications where some differences in the values of the static magneticproperties of the upper and lower magnetic films, due to grain growth inthe chromiumcopper alloy conducting layer, can be tolerated, forexample, in short stripline memory applications.

A reasonably satisfactory magnetostatically coupled thin-film magneticmemory device such as shown in FIG. 2 was constructed in the followingmanner. A magnetostrictive Permalloy material, 60% Ni/40% Fe, wasvacuum-deposited onto a glass substrate, at a temperature ofapproximately 280C, to a thickness of 2,000A to produce the lowermagnetic film. The composition of the deposited lower magnetic film was45% Ni/S 5% Fe. A chromium-copper alloy conducting layer was thenvacuum-deposited onto the lower magnetic film, from a chromium-coppermelt mixture, containing one-fourth percent percent chromium by weightto a thickness of 3,000A. The temperature of the assembly during thedeposition of the chromium-copper alloy conducting layer was 100C. Asecond magnetic film was then formed, on the chromium-copper alloyconducting layer, to a thickness of 2,000A by vacuumdepositingmagnetostrictive Permalloy material, again 60% Ni/40% Fe, at an assemblytemperature of approximately 280C. The composition of the depositedsecond magnetic film was 45% Ni/ 55% Fe. With the above materials andvalues, the wall-motion coercive force H of the second (upper) magneticfilm was 6 Oersteds, the angular dispersion ago was 4, and theanisotropy field l-l was 7 Oersteds. The corresponding values of H a andI-l for the first (lower) magnetic film were 5 Oersteds, 2, and 8Oersteds, respectively. As is evident from the above example, the valuesof the static magnetic properties of the upper and lower magnetic filmsdiffered from each other. However, experimentation has indicated thatthe differences are less than if a pure copper conducting layer wereused and, hence, the resulting device is considered more satisfactoryfor use as a magnetostatically coupled thin-film magnetic memory device.

Many variations are also possible in the abovedescribed specificexample. However, inasmuch as these variations are of the same nature asdiscussed hereinabove in connection with the first specific example, itis not believed that further discussion is necessary here.

What is claimed is:

l. A multilayer magnetic thin-film device including:

a first magnetic film;

a second magnetic film; and

a chromium-copper alloy conducting layer and a smoothing layer betweenthe first and second magnetic films, said smoothing layer directlycontacting the chromium-copper alloy conducting layer and the secondmagnetic film and smoothing the surface of the chromium-copper alloyconducting layer in contact therewith.

2. A multilayer magnetic thin-film device in accordance with claim 1wherein:

the chromium-copper alloy conducting layer is formed from achromium-copper mixture containing one-tenth to one-half of one percentchromium by weight.

3. A multilayer magnetic thin-film device in accordance with claim 1wherein:

the chromium-copper alloy conducting layer is formed from achromium-copper mixture containing about one-quarter of one percentchromium by weight.

4. A multilayer magnetic thinfilm device in accordance with claim 3wherein:

the first and second magnetic films are nickel-iron alloy films.

5. A multilayer magnetic thin-film device in accordance with claim 3wherein:

the first and second magnetic films are Cobaltnickel-iron alloy films.

6. A multilayer magnetic thin-film device in accordance with claim 3wherein:

the first and second magnetic films are manganesenickel-iron alloyfilms.

7. A multilayer magnetic thin-film device in accordance with claim 4wherein:

the smoothing layer is a silicon monoxide layer.

8. A multilayer magnetic thin-film device in accordance with claim 4wherein:

the first and second magnetic films are non-magnetostrictive nickel-ironalloy films.

9. A multilayer magnetic thin-film device in accordance with claim 7wherein:

the first and second magnetic films are magnetostrictive nickel-ironalloy films.

10. A magnetostatically coupled thin-film magnetic memory deviceincluding:

a first nickel-iron alloy magnetic storage film having a thickness of500-2,000A;

a chromium-copper alloy write-sense conducting layer disposed on thefirst nickel-iron alloy magnetic storage film and having a thickness of3,000A to 2 microns, said chromium-copper alloy write-sense conductinglayer being formed from a chromium-copper mixture containing fromonetenth to one-half of one percent of chromium by weight;

a silicon monoxide smoothing layer directly contacting thechromium-copper alloy write-sense conducting layer to smooth the surfaceof the chromium-copper alloy conducting layer in contact therewith andhaving a thickness of 1,50OA to 1.5

microns; and a second nickel-iron alloy magnetic storage film directlycontacting the silicon monoxide smoothing layer and having a thicknessof 5002,000A.

11. A magnetostatically coupled thin-film magnetic memory device inaccordance with claim 10 wherein:

the first and second nickel-iron alloy magnetic storage films are bothmagnetostrictive.

12. A multilayer magnetic thin-film device including:

a first magnetic film;

a second magnetic film; and

a chromium-copper alloy conducting layer between the first and secondmagnetic films, said chromi- 9 l um-copper alloy conducting layerdirectly contact- 18. A multilayer magnetic thin-film device in acingthe second magnetic film. cordance with claim 15 wherein: 13. Amultilayer magnetic thin-film device in acthe first and second magneticfilms are non-magcordance with 01mm 12 wh in: netostrictive nickel-ironalloy films.

the pp y condmftmg y r 1S 5 19. A multilayer magnetic thin-film devicein acformed from a chromium-copper mixture containcol-dance i h l i h ig file-tenth to One-half of one P chl'omlum the first and secondmagnetic films are magnetostricby welght; tive nickel-iron alloy films.A mPlnlayFr thm'film devlce m 20. A magnetostatically coupled thin-filmmagnetic cordance with claim 12 wherein: 10 memory device including:

the chromlum'copper cndu itmg layer 1s a first magnetostrictivenickel-iron alloy magnetic formed from a chromium-copper mixturecontamstorage film having a thickness of 2000A; about one-quarter of onepercent chromium by a chromium-copper alloy write-sense conducting i g'er ma netic thimfilm device in c 5 layer directly contacting the firstmagnetostrictive cordance withlclgim l4 5116mm a nickel-iron alloymagnetic storage film and having the first and second magnetic films arenickel-iron a thickness of sald chromlum-copper alloy write-senseconducting layer being formed alloy films. f h t t f 16. A multilayermagnetic thin-film device in acmm a c romlum'copper mm con ammg cordancewith claim 14 wherein: 2o one-tenth to one-half of one percent ofchromium by weight; and a second magnetostrictive nickel-iron alloymagnetic storage film having a thickness of 2,000A, said chromium-copperalloy conducting layer directly contacting said second magnetic film.

the first and second magnetic films are cobalt-nickeliron alloy films.

17. A multilayer magnetic thin-film device in accordance with claim 14wherein:

nickel-iron alloy films.

2. A multilayer magnetic thin-film device in accordance with claim 1wherein: the chromium-copper alloy conducting layer is formed from achromium-copper mixture containing one-tenth to one-half of one percentchromium by weight.
 3. A multilayer magnetic thin-film device inaccordance with claim 1 wherein: the chromium-copper alloy conductinglayer is formed from a chromium-copper mixture containing aboutone-quarter of one percent chromium by weight.
 4. A multilayer magneticthin-film device in accordance with claim 3 wherein: the first andsecond magnetic films are nickel-iron alloy films.
 5. A multilayermagnetic thin-film device in accordance with claim 3 wherein: the firstand second magnetic films are Cobalt-nickel-iron alloy films.
 6. Amultilayer magnetic thin-film device in accordance with claim 3 wherein:the first and second magnetic films are manganese-nickel-iron alloyfilms.
 7. A multilayer magnetic thin-film device in accordance withclaim 4 wherein: the smoothing layer is a silicon monoxide layer.
 8. Amultilayer magnetic thin-film device in accordance with claim 4 wherein:the first and second magnetic films are non-magnetostrictive nickel-ironalloy films.
 9. A multilayer magnetic thin-film device in accordancewith claim 7 wherein: the first and second magnetic films aremagnetostrictive nickel-iron alloy fIlms.
 10. A magnetostaticallycoupled thin-film magnetic memory device including: a first nickel-ironalloy magnetic storage film having a thickness of 500-2,000A; achromium-copper alloy write-sense conducting layer disposed on the firstnickel-iron alloy magnetic storage film and having a thickness of 3,000Ato 2 microns, said chromium-copper alloy write-sense conducting layerbeing formed from a chromium-copper mixture containing from one-tenth toone-half of one percent of chromium by weight; a silicon monoxidesmoothing layer directly contacting the chromium-copper alloywrite-sense conducting layer to smooth the surface of thechromium-copper alloy conducting layer in contact therewith and having athickness of 1,500A to 1.5 microns; and a second nickel-iron alloymagnetic storage film directly contacting the silicon monoxide smoothinglayer and having a thickness of 500-2,000A.
 11. A magnetostaticallycoupled thin-film magnetic memory device in accordance with claim 10wherein: the first and second nickel-iron alloy magnetic storage filmsare both magnetostrictive.
 12. A multilayer magnetic thin-film deviceincluding: a first magnetic film; a second magnetic film; and achromium-copper alloy conducting layer between the first and secondmagnetic films, said chromium-copper alloy conducting layer directlycontacting the second magnetic film.
 13. A multilayer magnetic thin-filmdevice in accordance with claim 12 wherein: the chromium-copper alloyconducting layer is formed from a chromium-copper mixture containingone-tenth to one-half of one percent chromium by weight.
 14. Amultilayer magnetic thin-film device in accordance with claim 12wherein: the chromium-copper alloy conducting layer is formed from achromium-copper mixture containing about one-quarter of one percentchromium by weight.
 15. A multilayer magnetic thin-film device inaccordance with claim 14 wherein: the first and second magnetic filmsare nickel-iron alloy films.
 16. A multilayer magnetic thin-film devicein accordance with claim 14 wherein: the first and second magnetic filmsare cobalt-nickel-iron alloy films.
 17. A multilayer magnetic thin-filmdevice in accordance with claim 14 wherein: the first and secondmagnetic films are manganese-nickel-iron alloy films.
 18. A multilayermagnetic thin-film device in accordance with claim 15 wherein: the firstand second magnetic films are non-magnetostrictive nickel-iron alloyfilms.
 19. A multilayer magnetic thin-film device in accordance withclaim 15 wherein: the first and second magnetic films aremagnetostrictive nickel-iron alloy films.
 20. A magnetostaticallycoupled thin-film magnetic memory device including: a firstmagnetostrictive nickel-iron alloy magnetic storage film having athickness of 2,000A; a chromium-copper alloy write-sense conductinglayer directly contacting the first magnetostrictive nickel-iron alloymagnetic storage film and having a thickness of 3,000A, saidchromium-copper alloy write-sense conducting layer being formed from achromium-copper mixture containing from one-tenth to one-half of onepercent of chromium by weight; and a second magnetostrictive nickel-ironalloy magnetic storage film having a thickness of 2,000A, saidchromium-copper alloy conducting layer directly contacting said secondmagnetic film.